<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        let num1 = +prompt('请输入第一个数字: ');
        let num2 = +prompt('请输入第二个数字: ');
        // 形参初始化(参数默认值)
        function getSumOfE1ToE2(e1 = 0,e2 = 0) {
            let sum = 0;
            for (let i = e1; i <= e2; i++) {
                sum += i;
            }
            return sum;
        }

        alert(num1 + '到' + num2 + '之间的和是：' + getSumOfE1ToE2(num1, num2));
        alert('默认值0到0之间的和是：' + getSumOfE1ToE2());
    </script>
</body>
</html>